U.S. patent application number 17/400256 was filed with the patent office on 2022-02-17 for electric heating device and method for manufacturing the same.
The applicant listed for this patent is Eberspacher catem GmbH & Co. KG. Invention is credited to Alfred Bluml, Karsten Bolz, Andreas Klingebiel, Dietmar Wunstorf.
Application Number | 20220053610 17/400256 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-17 |
United States Patent
Application |
20220053610 |
Kind Code |
A1 |
Klingebiel; Andreas ; et
al. |
February 17, 2022 |
Electric Heating Device and Method for Manufacturing the Same
Abstract
An electric heating device includes a housing with a partition
wall which separates a connection chamber from a heating chamber
for emitting heat. At least one heating assembly housing projects
from the partition wall in the direction of the heating chamber.
The heating assembly housing supports at least one PTC element and
strip conductors in an electrically insulated manner A housing wall
projecting from the partition wall and delimiting the connection
chamber and/or the heating chamber and/or the heating assembly
housing is connected to the partition wall by material bonding,
which may be by induction soldering. Also disclosed is a method of
making an electric heating device.
Inventors: |
Klingebiel; Andreas;
(Marbach am Neckar, DE) ; Wunstorf; Dietmar;
(Hildsheim, DE) ; Bolz; Karsten; (Kandel, DE)
; Bluml; Alfred; (Grunwald, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eberspacher catem GmbH & Co. KG |
Herxheim |
|
DE |
|
|
Appl. No.: |
17/400256 |
Filed: |
August 12, 2021 |
International
Class: |
H05B 3/06 20060101
H05B003/06; H05B 1/02 20060101 H05B001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 13, 2020 |
DE |
10 2020 210 284.8 |
Claims
1. An electric heating device comprising: a housing with a
partition wall which separates a connection chamber from a heating
chamber for emitting heat, wherein a housing wall at least
partially delimits one of the connection chamber and the heating
chamber, wherein at least one heating assembly housing projects
into the heating chamber from the partition wall; and at least one
PTC element and strip conductors which are supported in the heating
assembly housing in an insulated manner, the strip connectors being
electrically connected to the PTC element and being configured to
energize the PTC element with different polarities, wherein at
least one of the housing wall and the heating assembly housing is
connected to the partition wall in a materially bonded manner.
2. The electric heating device according to claim 1, wherein at
least one of the housing wall and the heating assembly housing is
inductively soldered to the partition wall.
3. The electric heating device according to claim 1, wherein the
housing wall delimits the connection chamber and the heating
chamber.
4. A method for manufacturing an electrical heating device, the
electrical heating device comprising a housing, a PTC element, and
strip conductors which are electrically connected to the PTC
element and which configured to energize the heating element with
different polarities, the housing including a partition wall
separating a connection chamber from a heating chamber for emitting
heat, wherein a housing wall at least partially delimits one of the
connection chamber and the heating chamber (10), wherein at least
one heating assembly housing projects from the partition wall into
the heating chamber, and wherein the PTC element and the strip
conductors are electrically connected in the connection chamber and
are supported in an insulated manner in the heating assembly
housing, the method comprising: providing the partition wall with
an opening for the electrical connection of the PTC element in the
connection chamber, and then soldering the housing wall or the
heating assembly housing to the partition wall.
5. The method according to claim 4, wherein the housing wall or the
heating assembly housing is inductively soldered to the partition
wall.
6. The method according to claim 4, wherein the housing wall and
the heating assembly housing are inductively soldered to the
partition wall.
7. The method according to claim 4, wherein, after soldering, the
PTC element and the strip conductors are inserted into the heating
assembly housing, and the strip conductors are electrically
connected in the connection chamber.
8. The method according to claim 4, wherein, during soldering, a
ring of solder is arranged adjacent to a gap between the partition
wall and the housing wall or the heating assembly housing and is
inductively melted so that the solder flows into the gap and
solidifies there.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to an electric heating device
with a housing which comprises a partition wall separating a
connection chamber from a heating chamber for emitting heat. At
least one PTC heating assembly projects from the partition wall in
the direction of the heating chamber. This PTC heating element is
exposed in the manner of a heating rib in the heating chamber. The
PTC heating assembly has at least one PTC element and strip
conductors electrically connected thereto, which are assigned
different polarities for energizing the PTC element. These strip
conductors are electrically connected to the power current in the
connection chamber.
2. Background of the Invention
[0002] Such a heating device is known, for example, from EP 2 337
425 A1. In such an electric heating device, the partition wall is
configured in one piece with a heating assembly housing, which
projects into the heating chamber as a heating rib. In the
aforementioned prior art, the partition wall is manufactured in one
piece together with the heating assembly housing by means of
aluminum die casting. This type of manufacturing requires a
considerable amount of aluminum. The electric heating device is
therefore relatively heavy. In the electric heating device
mentioned above, a plurality of heating assembly housings are
provided which project into the heating chamber as ribs closed at
their lower sides. Due to manufacturing requirements, these must be
spaced apart from one another by a certain distance, which is
contrary to the need for a compact construction.
[0003] In the variant according to EP 3 334 242 A1, a PTC heating
element is initially produced as a separate component and in this
form inserted in a heating element receptacle formed on the
partition wall so that the terminal end of the heating element
housing is accommodated in a sealed manner in the heating element
receptacle of the partition wall and the strip conductors are
exposed with their free, terminal ends in the connection chamber
where they can be electrically connected. In this prior art, the
preassembled PCT heating element is held positively in the heating
element receptacle, in which heating element receptacle the PCT
heating element is pressed.
[0004] This press-fitting receptacle requires a certain wall
thickness on the partition wall side. Furthermore, the tightness
between the PTC heating element and the heating element receptacle
is problematic in this configuration. At the temperatures
prevailing in operation, a seal made of a plastic material can age
so that there is a risk that the fluid to be heated will leak from
the heating chamber into the connection chamber. However, the
electrical connection of the PTC element to the power current takes
place in the connection chamber so that, with regard to operational
safety, no fluid may enter the connection chamber. Otherwise, a
short circuit is to be feared. Particularly, when the electric
heating device is used in an electrically powered vehicle in which
the on-board power supply is also used to operate the electric
heating device, such defects give rise to considerable safety
concerns.
SUMMARY
[0005] The present invention is based on the problem of providing a
compact electric heating device and a method for manufacturing the
same.
[0006] In order to solve the problem relating to the device, the
present invention discloses an electric heating device having a
housing with a partition wall which separates a connection chamber
from a heating chamber for emitting heat. A housing wall at least
partially delimits one of the connection chamber and the heating
chamber. At least one heating assembly housing projects into the
heating chamber from the partition wall. At least one PTC element
and strip conductors ware supported in the heating assembly housing
in an insulated manner. The strip connectors are electrically
connected to the PTC element and are configured to energize the PTC
element with different polarities. At least one of the housing wall
and the heating assembly housing is connected to the partition wall
in a materially bonded manner, such as by being inductively
soldered. The same applies additionally or alternatively to the
connection of the heating assembly housing to the partition
wall.
[0007] In contrast to the prior art discussed first, in which the
housing and also the heating rib are manufactured in one piece by
aluminum die casting, the present invention allows the subsequent
joining of components initially provided from thin sheet metal to
define the connection chamber and/or the heating chamber, or the
partition wall provided therebetween. The same applies to any
connecting ports projecting from a housing wall, for example for
fluid lines of a circulation circuit conducting the fluid to be
heated in the electric heating device. The electric heating device
according to the present invention is, in particular, an electric
heating device in a motor vehicle. Flexible hoses are typically
connected to and sealed against the respective connecting ports of
the electric heating device.
[0008] The sheet may have a wall thickness of less than 1
millimeter.
[0009] According to the procedure according to the invention, a
partition wall is first provided which will separate a connection
chamber from a heating chamber on the housing, wherein the
partition wall comprises at least one opening for the electrical
connection of the PTC element in the connection chamber. Through
this opening, the PTC element can be inserted into the heating
assembly housing from the side of the connection chamber. The
heating device assembly housing is usually closed on the lower
side, i.e. with its end lying in the heating chamber. The heating
assembly housing may be provided in this manner. The heating
assembly housing may be formed by a piece of cylindrical tubular
body cut to length, which can be closed on the lower side by
deforming the sheet material forming the heating assembly housing.
There, the sheet material may be bonded, soldered, welded, and/or
closed by beading or a plug inserted in a sealed manner. In the
method according to the invention, a housing wall is alternatively
or additionally connected to the partition wall by means of
induction soldering, wherein this housing wall can completely or
partially surround the connection chamber and/or the heating
chamber.
[0010] The solution according to the invention offers the
possibility of a more compact construction of an electric heating
device. In contrast to aluminum die castings, the individual
heating assembly housings can be provided on the partition wall
with a small distance between them. Induction soldering allows
locally limited heating so that good dimensional stability of the
previously manufactured components of the electric heating device
is ensured also after thermal joining. In addition, induction
soldering makes it possible to achieve a secure, fluid-tight
connection between the partition wall and the component connected
to it, for example the heating assembly housing or the housing
wall.
[0011] The low through heating of the joining partners during
induction soldering also allows local heating and thus a relatively
compact arrangement of several heating assembly housings connected
to the partition wall next to or behind one another. Accordingly,
the invention allows greater degrees of freedom in the design of
both the heating assembly housing and the housing of the entire
electric heating device. Compared to the prior art, the design of
the electric heating device according to the invention no longer
has to take into account the demolding of an aluminum housing
produced by means of die casting.
[0012] The procedure during induction soldering allows any
arbitrary type of temperature control, as long as it is only below
the melting point of the joining partners. These joining partners
are usually made of metal, typically a stamped metal sheet, which
is usually applied over the entire surface of the partition wall,
the heating element housing, and/or the housing wall.
[0013] Induction soldering results in a connection over the entire
surface and thus a tight connection between the partition wall, the
heating element housing and/or the housing wall. Induction
soldering can be carried out such that a contact element is applied
to the surface of the partition wall, the heating element housing
and/or the housing wall, if necessary after a certain amount of
preheating to reduce the soldering time. The joint is then heated
by induction so that the solder at the joint heats up and
liquefies. Capillary forces can draw the solder between the
surfaces to be joined and thus concentrate solder at the phase
boundary between the two joining partners of the solder joint.
[0014] In the method according to the invention, a ring of solder
may be arranged adjacent to a gap between the joining partners and
formed by the joining partners. An inductor is arranged
circumferentially on the outside or inside of the ring, which
inductively heats the solder and the joining partners enclosing a
gap between them in the area of the gap. As a result, the solder
flows into the gap, not least due to capillary action. The inductor
is switched on to heat the solder and the surfaces of the joining
partners defining the gap. After the solder has melted, the
inductor is switched off. The solder flows into the gap and
solidifies there.
[0015] The joining partners can consist of or contain non-ferrous
metals, ferrous metals, chromium-nickel steels and non-metallic
materials as well as any combination of these materials.
[0016] The soldering method according to the invention results in a
corrosion-resistant, in particular gas- and liquid-tight connection
between the joining partners. Compared with other material bonds
such as gluing or welding, the cycle time of the soldering method
is independent of the total length of the joint. Different
inductors can be used simultaneously. In this way, soldering can be
carried out simultaneously at different points. At the same time,
the heating is locally limited. This offers the possibility of
equipping the heating assembly housing before soldering. However,
equipping after soldering is preferable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Further details and advantages of the present invention
become evident from the following description of an embodiment in
connection with the drawing, which. Therein:
[0018] FIG. 1 shows a perspective view of an embodiment of an
electric heating device;
[0019] FIG. 2A shows a sectional view with a detail which
illustrates the connection between the partition wall and the
heating assembly housing;
[0020] FIG. 2B shows the detail III according to the illustration
in FIG. 2A;
[0021] FIG. 3 shows a view according to FIGS. 2A and 2B for a
variant before soldering (left) and after soldering (right);
[0022] FIG. 4 shows a variant with respect to the illustration
according to FIGS. 2A and 2B, wherein the state before soldering is
shown on the left and after soldering on the right;
[0023] FIG. 5 shows a sectional view of a further variant, wherein
the state before soldering is shown on the left and the state after
soldering on the right;
[0024] FIG. 6 shows a magnified sectional view of a transition
region between the partition wall and the heating assembly housing
with different variants for applying solder on the left and
right;
[0025] FIG. 7 shows a sectional view of a housing wall and a part
of a connecting port;
[0026] FIG. 8 shows a sectional view at the transition between the
housing upper part and the housing lower part;
[0027] FIG. 9 shows a variant for the illustration according to
FIG. 8; and
[0028] FIG. 10 shows a variant with respect to the illustration
according to FIG. 6.
DETAILED DESCRIPTION
[0029] In the Figure, reference sign 2 identifies a housing with a
housing upper part 4 and a housing lower part 6. The housing upper
part 4 surrounds a connection chamber 8. The housing lower part 6
surrounds a heating chamber 10. A partition wall 12 is located
between the heating chamber 10 and the connection chamber 8. The
partition wall 12 is fluid-tight so that liquid fluid contained in
the heating chamber 10, which is to be heated, cannot reach the
connection chamber 8. At the height of the heating chamber 10, the
housing 2 is towered above by connecting ports 14, which serve to
connect fluid-conducting lines within a motor vehicle. These
connecting ports 14 project from opposite housing walls 16, which
in the present case surround the heating chamber 6
circumferentially. In the Figure, only one of these connecting
ports 14 can be seen, namely partially sectioned.
[0030] Reference sign 18 identifies a heating assembly housing,
which in the present case is configured as a U-shaped pocket closed
on the lower side. In each of these heating assembly housings 18, a
plurality of PTC elements 20 are arranged one above the other in
the height direction of the heating assembly housing 18 and are
arranged between contact surfaces, which as strip conductors 22 are
in electrically conductive contact with the respective PTC elements
20 and are formed from a sheet material and form terminal lugs 23,
which are electrically conductively connected in the connection
chamber. Insulating layers 24 are located on the outside of the
respective strip conductor 22 so that heat emitted via main side
surfaces of the PTC elements first passes through the strip
conductor 22 and then through the insulating layer 24 and is
conducted through the walls of the heating assembly housing 18
projecting into the heating chamber 10 as a heating rib.
[0031] The heating assembly housing 18 is presently formed from a
relatively thin sheet material. The heating assembly housing 18
abuts against an outer surface of the respective insulating layer
24 without a gap there-between. The heating assembly housing 18 can
also abut against the respective insulating layer 24 under
pretension.
[0032] Compared with the prior art EP 2 337 425 A1, the mass of the
material forming the heating rib is significantly reduced. Thus,
the embodiment shown can be manufactured with less weight.
Moreover, a wedge element can be dispensed with, which according to
EP 2 337 425 A1 is pressed into the receiving pocket in order to
ensure good heat-conducting contact between the PTC element 20 and
the surfaces of the heating rib decoupling the heat.
[0033] The housing 2 also consists of a relatively thin sheet
material. Thus, the heating chamber 10 is circumferentially
surrounded by a basically cylindrical sheet metal sleeve which is
soldered, in particular induction soldered, to a base plate 26 of
the housing 2. The soldered joint is identified by reference sign
28.
[0034] The partition wall 12 is also formed from a relatively thin
sheet material and is soldered to the inner circumferential surface
of the housing 2 in a circumferentially fluid-tight manner. This
soldered joint is also identified by reference sign 28.
[0035] The heating assembly housing 18 is also soldered to the
partition wall 12. For this purpose, the heating assembly housing
18 is inserted into an opening 30 of the partition wall 12 before
being equipped with the PTC element(s) 20 and the strip conductors
22 as well as the insulating layers 24, and soldered therein to the
partition wall 12.
[0036] The connecting port 14 is soldered to the housing wall 16 in
the same way. Here, too, the soldering point is identified by
reference sign 28.
[0037] FIG. 2A shows a sectional view of the connection between the
partition wall 12 and the heating assembly housing 18. The
partition wall 12 is provided with a protruding connecting piece 32
by deep drawing. The connecting piece 32 is integrally formed on
the sheet metal part forming the partition wall 12. The connecting
piece 32 engages internally in the heating assembly housing 18.
[0038] FIG. 2A illustrates with reference sign 34 a ring of solder
material, the inner diameter of which is slightly larger than the
outer diameter of the heating assembly housing 18. The reference to
the diameter does not necessarily mean that the heating assembly
housing 18 or the ring 34 are formed circularly in the top view.
Rather, the ring 34 may also be formed polygonally, in particular
rectangularly.
[0039] Reference sign 36 characterizes an inductor. In the
embodiment shown, this inductor 36 for soldering is located within
a shielding gas housing 38, which essentially abuts sealingly on
the one hand against the lower side of the partition wall 12 facing
the heating chamber 10 and on the other hand against the outer
circumferential surface of the heating assembly housing 18. It goes
without saying that soldering is carried out before the base plate
26 is connected to the housing lower part 6.
[0040] For soldering, the inductor 36 is switched on, thereby
heating the solder as well as the overlapping walls in the area of
the connecting piece 32 and the heating assembly housing 18. Solder
material here is a high-temperature copper-based solder. During
soldering, the shielding gas housing 38 is flooded with shielding
gas. As a result of the heating by the inductor 36, the solder
melts and, due to capillary action, flows into a gap characterized
by reference sign 40 in FIG. 2B. The solder is characterized by
reference sign 42 in FIG. 2B. The solidified mold of the solder 42
shown in FIG. 2B is a natural result of the volume of solder 42
used on the one hand and the capillary action on the other.
[0041] FIG. 3 shows an alternative embodiment. Reference sign 18
shows the heating assembly housing on the inside; reference sign 32
shows the connecting piece on the outside. The ratios can also be
realized inversely, i.e. the connecting piece 32 can be realized
with smaller dimensions than the heating assembly housing 18. Only
a certain length piece with an overlap is essential. Reference sign
44 characterizes a solder support made of an electrically
non-conductive material. Due to this materiality, the solder
support 44 is not heated by the inductor 36. The ring 34 rests on a
surface of the solder support 44 before soldering. After switching
on the inductor 36 (not shown), the solder 42 flows into the gap 40
and solidifies there. This results in a fluid-tight secure
connection between the two overlapping sections of the connecting
piece 32 on the one hand and the heating assembly housing 18 on the
other.
[0042] A further variant with respect to the illustration according
to FIG. 2A is shown in FIG. 4. There, the solder in the form of the
ring 34 is located in a flanged receiving ring 46 before soldering
(left). After soldering, the solder has flowed into the gap 40. The
receiving ring 46 is emptied. It should be noted that solder has
also flowed between the end face of the flanged receiving ring 46
and the outer peripheral surface of the heating assembly housing
18. The variant according to FIG. 4 offers the advantage that the
ring 34 can be inserted into the annular gap between the outer and
the inner material. The abutting portions substantially seal the
accommodation area for the solder 42. This reduces environmental
influences during soldering in the area of the soldering point.
[0043] FIG. 5 shows another variant in which the heating assembly
housing 18 is accommodated within the connecting piece 32, which is
integrally formed with the partition wall 12. The overlapping
region extends substantially along the height extension of the
inductor 36. However, an edge region of the overlapping region
characterized by reference sign 47 is shown in the Figure at the
bottom, which is not covered by the action of the inductor 36.
Accordingly, the opposing joining partners are colder there so that
the solder 42 entering in molten form from above inevitably
solidifies in this region and prevents the solder 42 from flowing
out of the gap 40. The solder 42 cools--as FIG. 5 indicates on the
right--at a distance from the lower end of the overlapping
region.
[0044] FIG. 6 shows a variant in which the connecting piece 32 is
provided on the outside and the heating assembly housing 18 on the
inside. The heating assembly housing 18 is provided with a contact
flange characterized by reference sign 48. This contact flange 48
is also formed by bending sheet material forming the heating
assembly housing 18.
[0045] In FIG. 6, the ring 34 is arranged on the left in an annular
gap which is bounded in the longitudinal direction of the heating
assembly housing 18 by the contact flange 48 on the one hand and
the partition wall 12 on the other.
[0046] In the variant shown on the right in FIG. 6, the ring 34 is
located radially outside the contact flange 48 before soldering.
The inductor 36 is configured annularly and surrounds the outer
circumference of the contact flange 48. The partition wall 12 is
formed radially outside the contact flange 48 in the direction of
the heating chamber 10 to create an annular accommodation area 51
for the shaped inductor 36.
[0047] FIG. 7 shows a part of the connecting port 14 which is
provided with a widened contact flange 50. The housing wall 16 has
an outwardly chamfered bore 52. The ring 34 of solder is provided
between the material of the housing wall 16 bounding the bore 52
and the connecting port 14. In this embodiment, too, the solder
enters the gap 40 between the inner surface of the housing wall 16
and the contact flange 50 as a result of heating by the inductor 36
and due to capillary action.
[0048] A variant with respect to FIG. 7 is shown in FIG. 8. In this
variant, the housing lower part 6 is bent outwards to form a
receptacle 54 which is L-shaped in cross-section. The free end of
the housing upper part 4 is inserted in this L-shaped receptacle.
The free upper end of the housing lower part 6 is provided with a
funnel-shaped bend 56. The ring 34 is clamped therein before
soldering. The solder flows into the gap characterized by reference
sign 40 when the inductor 36 is activated.
[0049] FIG. 9 shows a variant. In this embodiment, the housing
upper part 4 and the housing lower part 6 each have opposite flange
surfaces 58, 60. The flange surface 60 of the housing lower part 6
is provided with a ring-shaped circumferential recess 62 in which
the ring 34 is accommodated.
[0050] FIG. 10 shows a further variant for connecting the heating
assembly housing 18 to the partition wall 12. Here, too, the
partition wall 12 has a connecting piece 32. However, this is
formed to taper inwardly at its free end. In a corresponding
manner, the heating assembly housing 18 is formed to taper
outwardly at its free end. This forming results in a
pre-positioning of the components joined in the longitudinal
direction of the heating assembly housing 18. The ring 34 is seated
between the free end of the heating assembly housing 18 and the
partition wall 12 extending thereabove prior to soldering.
* * * * *